Poly(methyl methacrylate) dielectric material applied in organic thin film transistors

The properties of pentacene-based organic thin film transistors (OTFTs) with poly(methyl methacrylate) (PMMA) as a dielectric layer have been investigated. Toluene was the best solvent for PMMA and the concentration of PMMA was about 8 wt % in toluene. The dielectric constant of PMMA dissolved in toluene was about 2.3. The pentacene film on the PMMA dielectric layer displayed high thin-film quality according to results of atomic force microscopy. The average grain size and surface roughness of pentacene grown on PMMA were about 0.29 mu m(2) and 10.26 nm, respectively. The pentacene-based OTFTs with PMMA as a dielectric layer exhibited excellent electric characteristics, including a high mobility of 0.241 cm(2) V-1 S-1 or larger, an on/off current ratio of 2 x 10(4) or larger, and a threshold voltage of less than -5.6 V.